Unit 3 – Stereochemistry . Stereoisomers Chirality (R) and (S) Nomenclature Depicting Asymmetric Carbons Diastereomers Fischer Projections Stereochemical Relationships Optical Activity Resolution of Enantiomers. Stereochemistry. Stereochemistry:
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
(R) and (S) Nomenclature
Depicting Asymmetric Carbons
Resolution of Enantiomers
Right hand threads slope up to the right.
Asymmetric (chiral) carbon
Example: Identify all asymmetric carbons present in the following compounds.
Example: Which of the following compounds contain an internal mirror plane of symmetry?
Example: Identify the following molecules as chiral or achiral.
I > Br > Cl > S > F > O > N > 13C > 12C > 3H > 2H > 1H
CH(CH3)2 > CH2CH2Br > CH3CH2
3(R) and (S) Nomenclature
Example: Identify the asymmetric carbon(s) in each of the following compounds and determine whether it has the (R) or (S) configuration.
Example: Name the following compounds.
Example: Draw a 3-dimensional formula for (R)-2-chloropentane.
Step 1:Identify the asymmetric carbon.
Step 2:Assign priorities to each group attached to the asymmetric carbon.
Step 3:Draw a “skeleton” with the asymmetric carbon in the center and the lowest priority group attached to the “dashed” wedge (i.e. pointing away from you).
Step 4:Place the highest priority group at the top.
Step 5:For (R) configuration, place the 2nd and 3rd priority groups around the asymmetric carbon in a clockwise direction.
Step 6:Double-check your structure to make sure that it has the right groups and the right configuration.
Example:The R-enantiomer of ibuprofen is not biologically active but is rapidly converted to the active (S) enantiomer by the body. Draw the structure of the R-enantiomer.
Example: Captopril, used to treat high blood pressure, has two asymmetric carbons, both with the S configuration. Draw its structure.